UK psychologists are to advise the Portuguese police on how best to handle England's football fans during Euro 2004 - assuming the team qualifies and is allowed to compete.
By Jonathan Amos
BBC News Online science staff, in Salford
There is a real fear that if hooligans run riot at their last away games - this weekend in Macedonia and in Turkey in October - then Beckham and co may be barred from the championships even if they top their group.
Understanding the dynamics of crowd behaviour
Scientists at Liverpool University say the behaviour of supporters at these crucial matches could depend critically on how they are marshalled by the police.
"If fans are met at airports by officers in riot gear it will not help the situation," said Dr Clifford Stott, from Liverpool University.
He said his team's in-depth studies of football crowd behaviour had shown that greeting travelling supporters with police wearing standard uniforms, standing in isolated pairs and smiling and talking with people helped to engender a better atmosphere and more friendly relations.
He said: "As the fans walk past, the police should smile and say 'hello'. Because what you are doing is setting in motion the nature of the relationship between police and fans - and it's a positive dynamic."
Dr Stott said it was important to stress his team's work did not blame police for the "disease" that often blights the English game.
But he said it was necessary to recognise the tactics used some times by the authorities to control expected disorder could actually create conditions where violence was more likely to emerge.
Dr Stott already advises UK agencies on security issues and will now give the benefit of his expertise to the police forces in Portugal's major cities.
He said the positioning, and the timing and style of deployment of horses, "snatch squads" and riot officers could help diffuse situations that might otherwise develop into bloody battles.
He said the success of the World Cup in Japan and Korea last year was in large part due to policing that was adjusted to meet the "actual levels of risk posed rather than perceived ones".
"This meant when the England fans did not present a risk there was a capability of toning down the policing to reflect that. It also helped hugely that we were in a country where the local population liked us.
"Contrast that with Marseille [during France 98] where groups of local youths were walking around with baseball bats indiscriminately attacking English fans."
Dr Stott said football hooliganism was a complex issue that defied simple explanations and solutions, but added that the scientific approach was revealing how crowd dynamics could be influenced to reduce the extent of the problem.
Japan/Korea was seen as a huge success
Dr Stott, an expert on the causes of riots, is talking about his research this coming week at the annual festival of the British Association for the Advancement of Science, held this year at Salford University in Manchester.
He said football fans could contribute to his team's research by completing an online survey (see internet links).